Reducing idle mode power consumption for monitoring neighboring base stations

ABSTRACT

A method for reducing idle mode power consumption is disclosed. An idle mode is entered. A neighboring base station is selected. If the selected neighboring base station is assigned a high-frequency monitoring mode, a signal strength of the neighboring base station is measured. A low-frequency monitoring mode is assigned to the selected neighboring base station if the signal strength of the selected neighboring base station has been below a power threshold for longer than a time threshold. Other aspects, embodiments, and features are also claimed and described.

RELATED APPLICATION & PRIORITY CLAIM

This application is related to and claims priority to U.S. ProvisionalPatent Application Ser. No. 61/345,555 filed May 17, 2010, for “ReducingIdle Mode Power Consumption.”

TECHNICAL FIELD

Embodiments of the present invention relate generally to communicationsystems, and more specifically to reducing idle mode power consumptionfor monitoring neighboring base stations or for other monitoringpurposes.

BACKGROUND

Electronic devices (cellular telephones, wireless modems, computers,digital music players, Global Positioning System units, Personal DigitalAssistants, gaming devices, etc.) have become a part of everyday life.Small computing devices are now placed in everything from automobiles tohousing locks. The complexity of electronic devices has increaseddramatically in the last few years. For example, many electronic deviceshave one or more processors that help control the device, as well as anumber of digital circuits to support the processor and other parts ofthe device.

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, video, data and so on.These systems may be multiple-access systems capable of supportingsimultaneous communication of multiple wireless communication deviceswith one or more base stations.

Mobile devices may have multiple modes of operation. For example, amobile device may be actively transmitting voice or data over a wirelesslink. Alternatively, a mobile device may be in an idle mode, where ithas limited functionality. Like other portable electronics, mobiledevices may have limited battery life. Therefore, benefits may berealized by reducing idle mode power consumption for monitoringneighboring base stations.

SUMMARY

Embodiments of the present invention generally include devices, methods,and systems configured to reduce idle mode power consumption levels.Typically wireless devices enter an idle mode when not activelycommunicating. Yet during idle mode, wireless device may be monitoringwireless signals. This monitoring may cause excessive or unwanted poweruse, and embodiments of the present invention enable reduction of idlemode power usage. Generally, a wireless device embodiment of theinvention can reduce power consumption based on a neighboring wirelessdevice's signal strength. If the neighboring wireless device's signalstrength is above or below a threshold, the wireless device embodimentcan modify (e.g., increase or decrease) the frequency it uses to monitorthe neighboring wireless device's signal strength. The wireless devicecan also assign frequency status identifiers or states to theneighboring wireless device to track its signal strength. The wirelessdevice can also be configured to monitor multiple neighbors. Additionalexemplary embodiments of the present invention are summarized below.

A method for reducing idle mode power consumption is disclosed. An idlemode is entered. A neighboring base station is selected. If the selectedneighboring base station is assigned a high-frequency monitoring mode, asignal strength of the neighboring base station is measured. Alow-frequency monitoring mode is assigned to the selected neighboringbase station if the signal strength of the selected neighboring basestation has been below a power threshold for longer than a timethreshold.

If, however, the selected neighboring base station is assigned thelow-frequency monitoring mode, the signal strength of the neighboringbase station may be measured if it is time to monitor the signalstrength. The high-frequency monitoring mode may be assigned to theselected neighboring base station if the signal strength of the selectedneighboring base station is above the power threshold.

A minimum number of power monitors may be performed per paging cycleonly if all neighboring base stations are in low-frequency monitoringmode. In contrast, more than the minimum number of power monitors may beperformed per paging cycle if at least one neighboring base station isassigned the high-frequency monitoring mode.

An idle mode timer may be maintained for each neighboring base station.The assigning of the low-frequency monitoring mode may include comparingthe idle mode timer for the selected base station with the timethreshold. The assigning of the high-frequency monitoring mode mayinclude resetting the idle mode timer for the selected neighboring basestation if the selected neighboring base station is above the powerthreshold. The power threshold and time threshold may be selected toachieve a power reduction in idle mode and maintain performanceindicators during operation. The method may be performed in a GlobalSystem for Mobile Communications (GSM) system.

A wireless communication device for reducing idle mode consumption isalso disclosed. The wireless communication device includes a processorand memory in electronic communication with the processor. Executableinstructions are stored in the memory. The instructions are executableto enter an idle mode. The instructions are also executable to select aneighboring base station. The instructions are also executable to, ifthe selected neighboring base station is assigned a high-frequencymonitoring mode, measure a signal strength of the neighboring basestation. The instructions are also executable to, if the selectedneighboring base station is assigned a high-frequency monitoring mode,assign a low-frequency monitoring mode to the selected neighboring basestation if the signal strength of the selected neighboring base stationhas been below a power threshold for longer than a time threshold.

A wireless communication device for reducing idle mode consumption isalso disclosed. The wireless communication device includes means forentering an idle mode. The wireless communication device also includesmeans for selecting a neighboring base station. The wirelesscommunication device also includes means for measuring, if the selectedneighboring base station is assigned a high-frequency monitoring mode, asignal strength of the neighboring base station. The wirelesscommunication device also includes means for assigning, if the selectedneighboring base station is assigned a high-frequency monitoring mode, alow-frequency monitoring mode to the selected neighboring base stationif the signal strength of the selected neighboring base station has beenbelow a power threshold for longer than a time threshold.

A computer-program product for reducing idle mode power consumption isalso disclosed. The computer-program product comprises a non-transitorycomputer-readable medium having instructions thereon. The instructionsinclude code for causing a wireless communication device to enter anidle mode. The instructions also include code for causing the wirelesscommunication device to select a neighboring base station. Theinstructions also include code for causing the wireless communicationdevice to measure, if the selected neighboring base station is assigneda high-frequency monitoring mode, a signal strength of the neighboringbase station. The instructions also include code for causing thewireless communication device to assign, if the selected neighboringbase station is assigned a high-frequency monitoring mode, alow-frequency monitoring mode to the selected neighboring base stationif the signal strength of the selected neighboring base station has beenbelow a power threshold for longer than a time threshold.

Other aspects and features of embodiments of the present invention willbecome apparent to those of ordinary skill in the art, upon reviewingthe following description of specific, exemplary embodiments of thepresent invention in concert with the various figures. While features ofthe present invention may be discussed relative to certain embodimentsand figures, all embodiments of the present invention can include one ormore of the discussed features. While one or more embodiments may bediscussed as having certain advantageous features, one or more of suchfeatures may also be used with the other discussed various embodiments.In similar fashion, while exemplary embodiments may be discussed belowas system or method embodiments it is to be understood that suchexemplary embodiments can be implemented in various devices, systems,and methods. Thus discussion of one feature with one embodiment does notlimit other embodiments from possessing and including that same feature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication system in which the methodsand apparatus disclosed herein may be utilized;

FIG. 2 is a block diagram illustrating a transmitter and a receiver in awireless communication system;

FIG. 3 is a block diagram illustrating a design of a receiver unit and ademodulator at a receiver;

FIG. 4 is a block diagram illustrating Time Division Multiple Access(TDMA) frame and burst formats in Global System for MobileCommunications (GSM);

FIG. 5 illustrates an example spectrum in a GSM system;

FIG. 6 is a block diagram illustrating a system for reducing idle modepower consumption;

FIG. 7 is a flow diagram illustrating a method for reducing idle modepower consumption;

FIG. 8 is a block diagram illustrating a wireless communication device;

FIG. 9A is a block diagram illustrating power monitors duringconsecutive paging cycles in a configuration with low-power neighboringbase stations;

FIG. 9B is a block diagram illustrating power monitors duringconsecutive paging cycles in a configuration with high-power neighboringbase stations; and

FIG. 10 illustrates certain components that may be included within awireless communication device.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

More and more people are using mobile communication devices, such as,for example, mobile phones, not only for voice, but also for datacommunications. In the Global System for Mobile Communications(GSM)/Enhanced Data rates for GSM Evolution (EDGE) Radio Access Network(GERAN) specification, General Packet Radio Service (GPRS) and EnhancedGPRS (EGPRS) provide data services. The standards for GERAN aremaintained by the 3GPP (Third Generation Partnership Project). GERAN isa part of GSM. More specifically, GERAN is the radio part of GSM/EDGEtogether with the network that joins the base stations (the Ater andAbis interfaces) and the base station controllers (A interfaces, etc.).GERAN represents the core of a GSM network. It routes phone calls andpacket data from and to the public switched telephone network (PSTN) andInternet to and from remote terminals. GERAN is also a part of combinedUMTS/GSM networks.

When in idle mode, wireless communication devices using 2^(nd)generation (2G) wireless telephone technology (e.g., GSM) may regularlymonitor the power of the neighboring cells, i.e., signal strength oftransmitting neighboring base stations. This is typically done when thewireless communication device “wakes up” to decode the paging channel.Power monitoring may draw extra power from the battery because itinvolves extra operation time for radio frequency (RF) components andbaseband processing components. Power monitoring may also lead toelongating the “awake time” when the amount of monitoring per pagingchannel (PCH) block is high. The idle mode current consumption thataffects the standby time of the wireless communication device is a keymeasure in design and manufacturing.

FIG. 1 illustrates a wireless communication system 100 in which themethods and apparatus disclosed herein may be utilized. The wirelesscommunication system 100 includes multiple base stations (BS) 102 a-cand multiple wireless communication devices 104 a-n. Each base station102 a-c provides communication coverage for a particular geographic area106 a-c. The term “cell” can refer to a base station 102 a-c and/or itscoverage area 106 a-c, depending on the context in which the term isused.

Wireless communication components discussed herein can be referred tousing the following terminology. For example, the term “wirelesscommunication device” 104 a-n refers to an electronic device that may beused for voice and/or data communication over a wireless communicationsystem 100. Examples of wireless communication devices 104 a-n includecellular phones, personal digital assistants (PDAs), handheld devices,wireless modems, laptop computers, personal computers, etc. A wirelesscommunication device 104 a-n may alternatively be referred to as anaccess terminal, a mobile terminal, a mobile station, a remote station,a user terminal, a terminal, a subscriber unit, a subscriber station, amobile device, a wireless device, user equipment (UE) or some othersimilar terminology. The term “base station” 102 a-c refers to awireless communication station that is installed at a fixed location andused to communicate with wireless communication devices 104 a-n. A basestation 102 a-c may alternatively be referred to as an access point, aNode B, an evolved Node B or some other similar terminology.

To improve system capacity, a base station 102 a-c coverage area 106 a-cmay be partitioned into multiple smaller areas, e.g., three smallerareas 108 a, 108 b and 108 c. Each smaller area 108 a, 108 b, 108 c maybe served by a respective base transceiver station (BTS). The term“sector” can refer to a BTS and/or its coverage area 108 a-c dependingon the context in which the term is used. For a sectorized cell, theBTSs for all sectors of that cell are typically co-located within thebase station 102 for the cell.

Wireless communication devices 104 a-n are typically dispersedthroughout the system 100. A wireless communication device 104 a-n maycommunicate with zero, one, or multiple base stations 102 a-c on thedownlink and/or uplink at any given moment.

For a centralized architecture, a system controller 110 may couple tothe base stations 102 a-c and provide coordination and control for thebase stations 102 a-c. The system controller 110 may be a single networkentity or a collection of network entities. For a distributedarchitecture, base stations 102 a-c may communicate with one another asneeded.

FIG. 2 is a block diagram illustrating a transmitter 218 and a receiver250 in a wireless communication system. For the downlink, thetransmitter 218 may be part of a base station 102 a-c, and receiver 250may be part of a wireless communication device 104 a-n. For the uplink,the transmitter 218 may be part of a wireless communication device 104a-n, and receiver 250 may be part of a base station 102 a-c.

In the transmitter 218, a transmit (TX) data processor 220 receives andprocesses (e.g., formats, encodes, and interleaves) data 274 andprovides coded data. A modulator 230 performs modulation on the codeddata and provides a modulated signal. Modulator 230 may perform Gaussianminimum shift keying (GMSK) for GSM, 8-ary phase shift keying (8-PSK)for Enhanced Data rates for Global Evolution (EDGE), etc. GMSK is acontinuous phase modulation protocol, whereas 8-PSK is a digitalmodulation protocol. A transmitter unit (TMTR) 232 conditions (e.g.,filters, amplifies, and upconverts) the modulated signal and generatesan RF-modulated signal, which is transmitted via an antenna 234.

At receiver 250, an antenna 252 receives RF-modulated signals fromtransmitter 218 and other transmitters. The antenna 252 may provide areceived RF signal to a receiver unit (RCVR) 254. The receiver unit 254conditions (e.g., filters, amplifies, and downconverts) the received RFsignal, digitizes the conditioned signal, and provides samples. Ademodulator 260 processes the samples as described below and providesdemodulated data. A receive (RX) data processor 270 processes (e.g.,deinterleaves and decodes) the demodulated data and provides decodeddata 272. In general, the processing by demodulator 260 and RX dataprocessor 270 is complementary to the processing by modulator 230 and TXdata processor 220, respectively, at transmitter 218.

Controllers/processors 240 and 280 direct operation at transmitter 218and receiver 250, respectively. Memory 242 and 282 may store programcodes in the form of computer software and data used by transmitter 218and receiver 250, respectively.

FIG. 3 is a block diagram illustrating a design of a receiver unit 354and a demodulator 360 at a receiver 350. Within the receiver unit 354, areceive chain 340 processes the received RF signal and provides Ibaseband signals (I_(bb)) 339 and Q baseband signals (Q_(bb)) 343.Receive chain 340 may perform low noise amplification, analog filtering,quadrature downconversion, etc. An analog-to-digital converter (ADC) 342digitalizes I_(bb) 339 and Q_(bb) 343 at a sampling rate of f_(adc)using a sampling clock 341 and provides input samples, which are denotedas I_(adc) 345 and Q_(adc) 347. In general, the ADC sampling ratef_(adc) may be related to the symbol rate f_(sym) by any integer ornon-integer factor.

Within demodulator 360, a pre-processor 320 performs pre-processing onthe I_(adc) 345 and Q_(adc) 347 from ADC 342. For example, apre-processor 320 may remove direct current (DC) offset, removefrequency offset, etc. An input filter 322 may filter the samples frompre-processor 320 based on a particular frequency response and providesinput I and Q samples, which are denoted as I_(in) 349 and Q_(in) 351.The input filter 322 may filter I_(in) 349 and Q_(in) 351 to suppressimages resulting from the sampling by the ADC 342 as well as jammers.The input filter 322 may also perform sample rate conversion, e.g., from24× oversampling down to 2× oversampling. A data filter 324 may filterI_(in) 349 and Q_(in) 351 from input filter 322 based on anotherfrequency response and provides output I and Q samples, which aredenoted as I_(out) 353 and Q_(out) 355. Filters 322 and 324 may beimplemented with finite impulse response (FIR) filters, infinite impulseresponse (IIR) filters or filters of other types. The frequencyresponses of filters 322 and 324 may be selected to achieve goodperformance. In one design, the frequency response of filter 322 isfixed, and the frequency response of filter 324 is configurable.

An adjacent channel interference (ACI) detector 330 can receive input Iand Q samples from the input filter 322, detects ACI in the received RFsignal and provides an ACI indicator 328 to filter 324. The ACIindicator 328 may indicate whether or not ACI is present and, ifpresent, whether the ACI is due to the higher RF channel centered at+200 KHz and/or the lower RF channel centered at −200 KHz. The frequencyresponse of filter 324 may be adjusted based on the ACI indicator 328,as described below, to achieve good performance.

An equalizer/detector 326 receives I_(out) 353 and Q_(out) 355 fromfilter 324 and performs equalization, matched filtering, detectionand/or other processing on these samples. For example,equalizer/detector 326 may implement a maximum likelihood sequenceestimator (MLSE) that determines a sequence of symbols that is mostlikely to have been transmitted given a sequence of I_(out) 353 andQ_(out) 355 and a channel estimate.

The Global System for Mobile Communications (GSM) is a widespreadstandard in cellular, wireless communication. GSM employs a combinationof Time Division Multiple Access (TDMA) and Frequency Division MultipleAccess (FDMA) for the purpose of sharing the spectrum resource. GSMnetworks typically operate in a number of frequency bands. For example,for uplink communication, GSM-900 commonly uses a radio spectrum in the890-915 MHz bands (mobile station to base transceiver station). Fordownlink communication, GSM 900 uses 935-960 MHz bands (base station tomobile station). Furthermore, each frequency band is divided into 200kHz carrier frequencies providing 124 RF channels spaced at 200 kHz.GSM-1900 uses the 1850-1910 MHz bands for the uplink and 1930-1990 MHzbands for the downlink. Like GSM 900, FDMA divides the spectrum for bothuplink and downlink into 200 kHz-wide carrier frequencies. Similarly,GSM-850 uses the 824-849 MHz bands for the uplink and 869-894 MHz bandsfor the downlink, while GSM-1800 uses the 1710-1785 MHz bands for theuplink and 1805-1880 MHz bands for the downlink.

An example of an existing GSM system is identified in technicalspecification document 3GPP TS 45.002 V4.8.0 (2003-06) titled “TechnicalSpecification 3rd Generation Partnership Project; TechnicalSpecification Group GSM/EDGE Radio Access Network; Multiplexing andmultiple access on the radio path (Release 4),” published by the 3rdGeneration Partnership Project (3GPP) standards-setting organization.

Each channel in GSM is identified by a specific absolute radio frequencychannel (ARFCN). For example, ARFCN 1-124 are assigned to the channelsof GSM 900, while ARFCN 512-810 are assigned to the channels of GSM1900. Similarly, ARFCN 128-251 are assigned to the channels of GSM 850,while ARFCN 512-885 are assigned to the channels of GSM 1800. Also, eachbase station 102 is assigned one or more carrier frequencies. Eachcarrier frequency is divided into eight time slots (which are labeled astime slots 0 through 7) using TDMA, such that eight consecutive timeslots form one TDMA frame with a duration of 4.615 ms. A physicalchannel occupies one time slot within a TDMA frame. Each active wirelessdevice/user is assigned one or more time slot indices for the durationof a call. User-specific data for each wireless device is sent in thetime slot(s) assigned to that wireless device and in TDMA frames usedfor the traffic channels.

Each time slot within a frame is also referred to as a “burst” in GSM.Each burst includes two tail fields, two data fields, a trainingsequence (or midamble) field and a guard period (GP). The number ofsymbols in each field is shown inside the parentheses. A burst includes148 symbols for the tail, data and midamble fields. No symbols are sentin the guard period. TDMA frames of a particular carrier frequency arenumbered and formed in groups of 26 or 51 TDMA frames calledmultiframes.

FIG. 4 is a block diagram illustrating Time Division Multiple Access(TDMA) frame 430 and burst 434 in Global System for MobileCommunications (GSM). The timeline for GSM transmission may be dividedinto multiframes 432. In one configuration, each multiframe 432 mayinclude 26 TDMA frames 430, which are labeled as TDMA frames 0 through25. Of the 26 TDMA frames 430, 24 may be TDMA frames for trafficchannels 436 (i.e., TDMA frames 0 through 11 and 13 through 24 of eachmultiframe). Additionally, one TDMA frame 438 may be for controlchannels (i.e., TDMA frame 12). TDMA frame 25 may be an idle TDMA frame439, which is used by the wireless devices to make measurements forneighbor base stations 102. Each TDMA frame 430 may include 8 TDMAbursts 434. Each TDMA burst 434 may fill one of eight time slots 435 ina TDMA frame 430 and may include tail bits, data bits, midamble bits andguard period (GP) bits.

FIG. 5 illustrates an example spectrum in a GSM system. In this example,five RF modulated signals are transmitted on five RF channels 540 a-ethat are spaced apart by 200 KHz. The RF channel of interest 540 c isshown with a center frequency of 0 Hz. The two adjacent RF channels 540b, 540 d have center frequencies that are +200 KHz and −200 KHz from thecenter frequency of the desired RF channel 540 c. The next two nearestRF channels 540 a, 540 e (which are referred to as blockers ornon-adjacent RF channels) have center frequencies that are +400 KHz and−400 KHz from the center frequency of the desired RF channel 540 c.There may be other RF channels in the spectrum, which are not shown inFIG. 5 for simplicity. The non-desired channels 540 a-b, 540 d-e maycarry adjacent channel interference (ACI) relative to the desiredchannel 540 c. In GSM, an RF-modulated signal is generated with a symbolrate of f_(sym)=13000/40=270.8 kilo symbols/second (Ksps) and has a −3dB bandwidth of up to +/−135 KHz. The RF-modulated signals on adjacentRF channels 540 may thus overlap one another at the edges, as shown inFIG. 5.

One or more modulation schemes may be used in GSM to communicateinformation such as voice, data, and/or control information. Examples ofthe modulation schemes may include GMSK (Gaussian Minimum Shift Keying),M-ary QAM (Quadrature Amplitude Modulation) or M-ary PSK (Phase ShiftKeying), where M=2^(n), with n being the number of bits encoded within asymbol period for a specified modulation scheme. GMSK is a constantenvelope binary modulation scheme allowing raw transmission at a maximumrate of 270.83 kilobits per second (Kbps).

GSM is efficient for standard voice services. However, high-fidelityaudio and data services desire higher data throughput rates due toincreased demand on capacity to transfer both voice and data services.To increase capacity, the General Packet Radio Service (GPRS), EDGE(Enhanced Data rates for GSM Evolution) and UMTS (Universal MobileTelecommunications System) standards have been adopted in GSM systems.

General Packet Radio Service (GPRS) is a non-voice service. It allowsinformation to be sent and received across a mobile telephone network.It supplements Circuit Switched Data (CSD) and Short Message Service(SMS). GPRS employs the same modulation schemes as GSM. GPRS allows foran entire frame (all eight time slots) to be used by a single mobilestation at the same time. Thus, higher data throughput rates areachievable.

EDGE uses both the GMSK modulation and 8-PSK modulation. The modulationtype can be changed from burst to burst. 8-PSK modulation in EDGE is alinear, 8-level phase modulation with 3π/8 rotation, while GMSK is anon-linear, Gaussian-pulse-shaped frequency modulation. However, thespecific GMSK modulation used in GSM can be approximated with a linearmodulation (i.e., 2-level phase modulation with a π/2 rotation). Thesymbol pulse of the approximated GSMK and the symbol pulse of 8-PSK areidentical.

In GSM/EDGE, frequency bursts (FB) are sent regularly by the basestation (BS) 102 to allow mobile stations (MS) to synchronize theirlocal oscillator (LO) to the base station 102 LO, using frequency offsetestimation and correction. These bursts comprise a single tone, whichcorresponds to all “0” payload and training sequence. The all-zeropayload of the frequency burst is a constant frequency signal, or asingle tone burst. When in power mode, the remote terminal huntscontinuously for a frequency burst from a list of carriers. Upondetecting a frequency burst, the MS will estimate the frequency offsetrelative to its nominal frequency, which is 67.7 KHz from the carrier.The MS LO will be corrected using this estimated frequency offset.

FIG. 6 is a block diagram illustrating a system 600 for reducing idlemode power consumption. The system 600 may include a wirelesscommunication device 602 that communicates with a serving base station604 and one or more of the above discussed components. The serving basestation 604 may communicate with a base station controller (BSC) 607(also referred to as a radio network controller or packet controlfunction). The base station controller 607 may communicate with a mobileswitching center (MSC) 608, a packet data serving node (PDSN) 610 orinternetworking function (IWF), a public switched telephone network(PSTN) 614 (typically a telephone company) and an Internet Protocol (IP)network 612 (typically the Internet). The mobile switching center (MSC)608 may be responsible for managing communication between the wirelesscommunication device 602 and the public switched telephone network 614.The packet data serving node 610 may be responsible for routing packetsbetween the wireless communication device 602 and the IP network 612.

The wireless communication device 602 may also monitor the power (e.g.,signal strength) of one or more neighboring base stations 606 a-b. Thismay include using a neighboring base station monitoring module 611. Aneighboring base station's 606 a-b signal strength may be determined bymonitoring a beacon channel, e.g., the Broadcast Control Channel (BCCH).The wireless communication device 602 may include a neighboring basestation monitoring module 611. The neighboring base station monitoringmodule 611 may reduce the frequency of power monitoring for neighboringbase stations 606 a-b based on the signal strengths of neighboring basestations 606 a-b. For example, when the neighboring base stations' 606a-b signal strengths are weak (e.g., as compared to a power threshold),the wireless communication device 602 may reduce the frequency withwhich it monitors that neighboring base stations' 606 a-b signalstrengths. Frequency reduction can reduce power consumption in thewireless communication device 602.

Utilized power thresholds can have varying aspects. For example, autilized power threshold may be a value below which a neighboring basestation 606 a-b ceases to be a candidate for reselection, i.e., aneighboring base station 606 a-b with a signal strength below the powerthreshold is not likely to become the serving base station 604. In someembodiments, utilized thresholds can be a static threshold and set at astatic level of, for example, approximately −107 dBm. Other staticthreshold levels can also be used. Threshold levels can also be dynamicin certain instances. For example, a threshold can be dynamic based onchances of acquiring one or more neighbors at low powers. In areas wherestrong interference is present, increasing a utilized threshold in adynamic fashion may be desired. In addition, in some embodiments use ofalternating static and dynamic thresholds may be utilized as desired.

The wireless communication device 602 may maintain a timer on all theneighboring base stations 606 a-b when it enters idle mode. If aneighboring base station's 606 a-b signal strength is consistently belowthe power threshold for a certain period, the neighboring base station606 a-b may be assigned a low-frequency monitoring mode. If aneighboring base station 606 a-b assigned to a low-frequency monitoringmode exhibits a higher-than-threshold power at any time, it may bere-assigned to the normal high-frequency monitoring mode. At such atime, the neighboring base station 606 a-b may again become a candidatefor the low-frequency monitoring mode. The frequency of monitoring inthe low-frequency monitoring mode and high-frequency monitoring mode maycomply with the 3^(rd) Generation Partnership Project (3GPP)specifications and may be determined based on achieving a desirablebalance between reducing the power consumption and maintaining the keyperformance indicators in the field.

In one configuration, the wireless communication device 602 may have aminimum number of power monitors per paging cycle and a maximum numberof power monitors per paging cycle, e.g., based on 3GPP specifications.Based on the modes (high-frequency monitoring mode or low-frequencymonitoring mode) of the neighboring base stations 606 a-b, the wirelesscommunication device 602 may perform a number of monitors that isbetween the minimum and the maximum. For example, the minimum number ofmonitors per paging cycle may be 1.5, i.e., one power monitor during afirst paging cycle, two power monitors during a second paging cycle, oneduring a third paging cycle, two power monitors during a fourth pagingcycle, etc. A maximum number of power monitors per paging cycle may beseven. If all neighboring base stations 606 a-b were in high-frequencymode, the wireless communication device 602 may perform seven powermonitors per paging cycle. Alternatively, if all the neighboring basestations 606 a-b were in low-frequency mode, the wireless communicationdevice 602 may perform 1.5 power monitors per paging cycle.Alternatively, if some of the neighboring base stations 606 a-b were inlow-frequency mode while some of the neighboring base stations 606 a-bwere in high-frequency mode, the wireless communication device 602 mayperform somewhere between 1.5 and 7 power monitors per paging cycle.

FIG. 7 is a flow diagram illustrating a method 700 for reducing idlemode power consumption. The method 700 may be performed by the wirelesscommunication device 602 illustrated in FIG. 6. The wirelesscommunication device 602 may enter 702 idle mode. In idle mode, thewireless communication device 602 may monitor the signal strength ofneighboring base stations 606 a-b. This monitoring may consume powerresources from the battery. The method 700 may reduce idle mode powerconsumption by selectively reducing the frequency with which someneighboring base stations 606 a-b are monitored.

Upon entering idle mode, the wireless communication device 602 may start704 an idle mode timer for each neighboring base station. The idle modetimers may keep track of how long a particular neighboring basestation's signal strength is below a power threshold. The wirelesscommunication device 602 may select 706 a neighboring base station 606a-b and determine 708 if the selected neighboring base station isassigned high-frequency or low-frequency monitoring. If the selectedneighboring base station 606 a-b is assigned a high-frequency monitoringmode, the wireless communication device 602 may measure 710 the signalstrength of the selected neighboring base station 606 a-b. The wirelesscommunication device 602 may also determine 712 if the signal strengthof the neighboring base station 606 a-b is less than a power threshold.The power threshold may be any suitable value, e.g., 110 dB. If thesignal strength of the neighboring base station 606 a-b is not less thana power threshold, the wireless communication device 602 may assign 714a high-frequency monitoring mode to the selected neighboring basestation 606 a-b and reset the neighboring base station's idle modetimer. On the other hand, if the signal strength of the neighboring basestation 606 a-b is less than the power threshold, the wirelesscommunication device 602 may determine 716 if the selected neighboringbase station's idle mode timer is greater than a time threshold. If not,the wireless communication device 602 may select 706 a new neighboringbase station 606 a-b. If yes, the wireless communication device 602 mayassign 718 a low-frequency monitoring mode to the neighboring basestation 606 a-b. The time threshold may be any suitable value, e.g., 30seconds. Once the monitoring mode has been assigned, the wirelesscommunication device 602 may determine 720 if there are more neighboringbase stations 606 a-b, and select 706 a new neighboring base station 606a-b if applicable.

If a selected neighboring base station 606 a-b is assigned alow-frequency monitoring mode, the wireless communication device 602 maydetermine 722 if it is time to monitor the signal strength of theselected neighboring base station 606 a-b. If not, the wirelesscommunication device 602 may select 706 a new neighboring base station606 a-b. If yes, the wireless communication device 602 may measure 724the signal strength of the selected neighboring base station 606 a-b.Alternatively, the determination of whether it is time to monitor maynot be performed. The wireless communication device 602 may alsodetermine 726 whether the signal strength of the neighboring basestation 606 a-b is greater than the power threshold. If not, thewireless communication device 602 may assign 714 the low-frequencymonitoring mode to the neighboring base station 606 a-b. If, however,the signal strength of the selected neighboring base station 606 a-b isgreater than the power threshold, the wireless communication device 602may assign 728 the high-frequency monitoring mode to the selectedneighboring base station 606 a-b and reset the neighboring basestation's idle mode timer. The wireless communication device 602 mayalso determine 720 if there are more neighboring base stations 606 a-b.

The wireless communication device 602 may maintain a timer and assign amonitoring mode for each individual neighboring base station 606 a-b.When the signal strength for a particular neighboring base station 606a-b falls below the power threshold for longer than the timer threshold,it is assigned to a low-monitoring mode. The neighboring base station606 a-b may then be re-assigned to the high-monitoring mode when thesignal strength again exceeds the power threshold. Therefore, in oneconfiguration, the frequency of monitoring is handled on an individualneighboring base station 606 a-b basis. For example, the frequency thata wireless communication device 602 monitors a first neighboring basestation 606 a-b is unaffected by a second neighboring base station 606a-b entering a low-monitoring mode, i.e., the monitoring mode for anindividual neighboring base station 606 a-b is independent of monitoringmodes for others.

Alternatively, the signal strengths of all neighboring base stations 606a-b may be used together to determine the number of power monitorsperformed per paging cycle. For example, the wireless communicationdevice 602 may reduce the number of power monitors performed per pagingcycle only if the signal strength of all neighboring base stations 606a-b is below a threshold power for a threshold time. The wirelesscommunication device 602 may then increase the number of power monitorsperformed during each paging cycle when the signal strength of anysingle neighboring base station 606 a-b rises above the power threshold.In this configuration, the signal strength of a first neighboring basestation may affect the frequency with which a second neighboring basestation 606 a-b is monitored.

For example, in one configuration, a paging cycle may be 2 seconds long,as determined by a serving base station 604. In this configuration, thewireless communication device 602 may have 15 neighbors. If, based onthe number of high-frequency monitoring mode and low-frequencymonitoring mode neighboring base stations, the wireless communicationdevice 602 performs 1.5 power monitors per paging cycle, it may take 10paging cycles (20 seconds) for all neighboring base stations to bemonitored. In other words, the wireless communication device 602 mayalternate between performing one power monitor in a paging cycle and 2power monitors in a paging cycle. This may be a configuration withrelatively weak neighboring base station signals. On the other hand, ifneighboring base stations had relatively strong signal strengths, thewireless communication device 602 may perform 7 power monitors perpaging cycle.

FIG. 8 is a block diagram illustrating a wireless communication device802. The wireless communication device 802 may include neighboring basestation data 830 and a neighboring base station monitoring module 811.This data 830 may include an identifier 832, an idle mode timer 834 a, abeacon signal strength 836 a, and a mode assignment 838 a for eachneighboring base station 606 a-b. The identifier 832 may be a code thatuniquely identifies each neighboring base station 606 a-b in thewireless communication system. In one configuration, a Base StationIdentity Code (BSIC) sent on a beacon channel, such as the BroadcastControl Channel (BCCH), may be used as the identifier 832. The wirelesscommunication device 802 may determine a beacon signal strength 836 afrom the beacon channel and associate it with a particular neighboringbase station 606 a-b using the identifier 832. The idle mode timer 834 amay be an incrementing timer maintained by the wireless communicationdevice 802 for each neighboring base station 606 a-b. The modeassignment 838 a may be a determination that a particular neighboringbase station 606 a-b should be in a high-frequency monitoring mode or alow-frequency monitoring mode.

The neighboring base station monitoring module 811 may determine themode assignments 838 a-b and the number of power monitors per pagingcycle (Y) 852 based on neighboring base station data 830. Specifically,a signal strength calculator 842 may determine beacon signal strengths836 b for neighboring base stations 606 a-b from the beacon signals 840,e.g., the signals transmitted on a beacon channel such as the BroadcastControl Channel (BCCH). Along with the idle mode timers 834 b for eachneighboring base station 606 a-b, a power threshold 844 and a timerthreshold 846, a mode assignment module 848 may use the beacon signalstrength 836 b to determine the mode assignment for each selectedneighboring base station 606 a-b. Specifically, the mode assignmentmodule 848 may assign all neighboring base stations 606 a-b with asufficient beacon signal strength 836 b to a high-frequency monitoringmode, i.e., all neighboring base stations 606 a-b with a beacon signalstrength 836 b higher than the power threshold 844 or lower than thepower threshold 844 for less than the timer threshold 846. The modeassignment module 848 may assign all neighboring base stations 606 a-bwith a consistently low beacon signal strength 836 b to a low-frequencymonitoring mode, i.e., all neighboring base stations 606 a-b with beaconsignal strengths 836 b that have been lower than the power threshold 844for longer than the timer threshold 846. The power threshold 844 andtimer threshold 846 may be selected to achieve a power reduction in idlemode and maintain performance indicators during operation. A powermonitoring frequency module 850 may determine the number of powermonitors to perform per paging cycle (Y) 852 (e.g., between 1.5 and 7)based on the mode assignments 838 b.

FIG. 9A is a block diagram illustrating power monitors duringconsecutive paging cycles 954 a-h in a configuration with low-powerneighboring base stations 606 a-b. More specifically, FIG. 9Aillustrates power monitors performed during consecutive paging cycles bya wireless communication device 602 with all neighboring base stations606 a-b in low-frequency monitoring mode. For example, this may occurwhen the beacon signal strengths 836 a-b of all neighboring basestations 606 a-b are below a power threshold 844 for longer than a timerthreshold 846, e.g., in an underground parking garage. In FIG. 9A, “N1”indicates a power monitor performed for the first neighboring basestation 606 a-b, “N2” indicates a power monitor performed for the secondneighboring base station 606 a-b, etc. Therefore, FIG. 9A is illustratedfor a wireless communication device 602 having 10 neighboring basestations 606 a-b, although the present systems and methods may be usedfor any number of neighboring base stations 606 a-b.

In this configuration, the wireless communication device 602 may performthe minimum number of allowed power monitors every paging cycle 954 a-h,shown as 1.5 power monitors per paging cycle. In other words, the numberof power monitors per paging cycle (Y) 852 equals the minimum number ofallowed power monitors, e.g., as defined in the 3GPP specification. Thewireless communication device 802 may perform a power monitor for thefirst neighboring base station 606 a-b (N1) during a first paging cycle954 a, a power monitor for the second neighboring base station 606 a-b(N2) and the third neighboring base station 606 a-b (N3) during a secondpaging cycle 954 b, etc. Therefore, in this configuration with low-powerneighboring base stations 606 a-b, all neighboring base stations 606 a-bmay be monitored at least every seven paging cycles 954 a-h. In oneexample, a GSM paging cycle 954 a-h may range from about 470milliseconds (2 multiframes×51 frames per multiframe×4.6 millisecondsper frame) to 2.1 seconds (9 multiframes×51 frames per multiframe×4.6milliseconds per frame). Therefore, in a ten-neighbor configuration thatperforms 1.5 power monitors per paging cycle 954 a-h, each neighboringbase station 606 a-b may be monitored about every 3.2 seconds (470milliseconds per paging cycle×6.75 paging cycles, on average, to monitorall ten neighbors) to 14.2 seconds (2.1 seconds per paging cycle×6.75paging cycles, on average, to monitor all ten neighbors), depending onthe duration of the paging cycles 954 a-h. This reduction in powermonitors performed may result in reduced current consumption in awireless communication device 602. It may also reduce the “awake” timein a wireless communication device 602, thus allowing select componentsto remain in a sleep mode and save even more power.

FIG. 9B is a block diagram illustrating power monitors duringconsecutive paging cycles 956 a-b in a configuration with all high-powerneighboring base station 606 a-b. More specifically, FIG. 9B illustratespower monitors performed during consecutive paging cycles by a wirelesscommunication device 602 with all neighboring base stations 606 a-b inhigh-frequency monitoring mode. For example, this may occur when thebeacon signal strengths 836 a-b of all neighboring base stations 606 a-bare above a power threshold 844 or below the power threshold 844 forless than a timer threshold 846. As in FIG. 9A, “N1” indicates a powermonitor performed for the first neighboring base station 606 a-b, “N2”indicates a power monitor performed for the second neighboring basestation 606 a-b, etc. Specifically, FIG. 9B illustrates power monitorsperformed during consecutive paging cycles by a wireless communicationdevice 602 with ten neighboring base stations 606 a-b, all ten of whichare in high-frequency monitoring mode.

In this configuration, the wireless communication device 602 may performthe maximum number of allowed power monitors every paging cycle 956 a-b,shown as 7 power monitors per paging cycle 956 a-b. In other words, thenumber of power monitors per paging cycle (Y) 852 equals the maximumnumber of allowed power monitors, e.g., as defined in section 6.6.1 in3GPP TS 45.008. As used herein, the “maximum” number of allowed monitorsrefers to the highest number of power monitors required by the relevantspecification for a paging cycle, i.e., to comply with a worst caseconfiguration. There may not be an upper limit restriction for thenumber of power monitors allowed per paging cycle (i.e., if powerconsumption is not a concern, the wireless communication device 602 mayexceed the “maximum” number), but the “maximum” number used hereinrefers to the most power monitors that may ever be required of thewireless communication device 602. In other words, if a wirelesscommunication device 602 performs the maximum number of monitors(illustrated as 7 monitors per paging cycle 956 a-b in FIG. 9B), thewireless communication device 602 will comply with even the mostrigorous requirement in the specification, i.e., the maximum number ofmonitors will comply with the worst case scenario (defined in therelevant specification) for number of neighbors and paging cycle 956 a-blength.

In the ten-neighbor configuration illustrated in FIG. 9B, The wirelesscommunication device 802 may perform a power monitor for the firstthrough seventh neighboring base stations 606 a-b (N1-N7) during a firstpaging cycle 956 a and a power monitor for the eighth through tenthneighboring base station 606 a-b (N8-N10) before starting over again,i.e., power monitors for the first through fourth neighboring basestations 606 a-b (N1-N4) may be performed in the second paging cycle 956b following the power monitors for the eighth through tenth neighboringbase stations 606 a-b (N8-N10). Therefore, in this configuration withhigh-power neighboring base stations 606 a-b, all neighboring basestations 606 a-b may be monitored at least every two paging cycles 956a-b. In one example, a GSM paging cycle 956 a-b may range from about 470milliseconds to 2.1 seconds, as discussed above. Therefore, in aten-neighbor configuration that performs 7 power monitors per pagingcycle 956 a-b, each neighboring base station 606 a-b may be monitoredabout every 670 milliseconds (470 milliseconds per paging cycle×1.43paging cycles to monitor all ten neighbors) to 3 seconds (2.1 secondsper paging cycle×1.43 paging cycles to monitor all ten neighbors),depending on the duration of the paging cycles 956 a-b.

While FIG. 9A illustrates a minimum monitoring mode and FIG. 9Billustrates a maximum monitoring mode, the present systems and methodsmay operate between the minimum and maximum. For example, the wirelesscommunication device 602 may perform 5 power monitors per paging cycle.In a ten-neighbor configuration that performs 5 power monitors perpaging cycle (not shown), each neighboring base station 606 a-b may bemonitored about every 940 milliseconds (470 milliseconds per pagingcycle×2 paging cycles to monitor all ten neighbors) to 4.2 seconds (2.1seconds per paging cycle×2 paging cycles to monitor all ten neighbors),depending on the duration of the paging cycles.

FIG. 10 illustrates certain components that may be included within awireless communication device 1004. The wireless communication device1004 may be an access terminal, a mobile station, a user equipment (UE),etc. For example, the wireless communication device 1004 may be thewireless communication device 802 illustrated in FIG. 8. The wirelesscommunication device 1004 includes a processor 1003. The processor 1003may be a general purpose single- or multi-chip microprocessor (e.g., anARM), a special purpose microprocessor (e.g., a digital signal processor(DSP)), a microcontroller, a programmable gate array, etc. The processor1003 may be referred to as a central processing unit (CPU). Althoughjust a single processor 1003 is shown in the wireless communicationdevice 1004 of FIG. 10, in an alternative configuration, a combinationof processors (e.g., an ARM and DSP) could be used.

The wireless communication device 1004 also includes memory 1005. Thememory 1005 may be any electronic component capable of storingelectronic information. The memory 1005 may be embodied as random accessmemory (RAM), read-only memory (ROM), magnetic disk storage media,optical storage media, flash memory devices in RAM, on-board memoryincluded with the processor, EPROM memory, EEPROM memory, registers andso forth, including combinations thereof.

Data 1007 a and instructions 1009 a may be stored in the memory 1005.The instructions 1009 a may be executable by the processor 1003 toimplement the methods disclosed herein. Executing the instructions 1009a may involve the use of the data 1007 a that is stored in the memory1005. When the processor 1003 executes the instructions 1009 a, variousportions of the instructions 1009 b may be loaded onto the processor1003, and various pieces of data 1007 b may be loaded onto the processor1003.

The wireless communication device 1004 may also include a transmitter1011 and a receiver 1013 to allow transmission and reception of signalsto and from the wireless communication device 1004. The transmitter 1011and receiver 1013 may be collectively referred to as a transceiver 1015.Multiple antennas 1017 a-b may be electrically coupled to thetransceiver 1015. The wireless communication device 1004 may alsoinclude (not shown) multiple transmitters, multiple receivers, multipletransceivers and/or additional antennas.

The wireless communication device 1004 may include a digital signalprocessor (DSP) 1021. The wireless communication device 1004 may alsoinclude a communications interface 1023. The communications interface1023 may allow a user to interact with the wireless communication device1004.

The various components of the wireless communication device 1004 may becoupled together by one or more buses, which may include a power bus, acontrol signal bus, a status signal bus, a data bus, etc. For the sakeof clarity, the various buses are illustrated in FIG. 10 as a bus system1019.

The term “coupled” encompasses a wide variety of connections. Forexample, the term “coupled” should be interpreted broadly to encompasscircuit elements directly connected to each other and circuit elementsindirectly connected via other circuit elements.

The term “determining” encompasses a wide variety of actions and,therefore, “determining” can include calculating, computing, processing,deriving, investigating, looking up (e.g., looking up in a table, adatabase or another data structure), ascertaining and the like. Also,“determining” can include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” can include resolving, selecting, choosing, establishingand the like.

The phrase “based on” does not mean “based only on,” unless expresslyspecified otherwise. In other words, the phrase “based on” describesboth “based only on” and “based at least on.”

The term “processor” should be interpreted broadly to encompass ageneral purpose processor, a central processing unit (CPU), amicroprocessor, a digital signal processor (DSP), a controller, amicrocontroller, a state machine and so forth. Under some circumstances,a “processor” may refer to an application specific integrated circuit(ASIC), a programmable logic device (PLD), a field programmable gatearray (FPGA), etc. The term “processor” may refer to a combination ofprocessing devices, e.g., a combination of a DSP and a microprocessor, aplurality of microprocessors, one or more microprocessors in conjunctionwith a DSP core or any other such configuration.

The term “memory” should be interpreted broadly to encompass anyelectronic component capable of storing electronic information. The termmemory may refer to various types of processor-readable media such asrandom access memory (RAM), read-only memory (ROM), non-volatile randomaccess memory (NVRAM), programmable read-only memory (PROM), erasableprogrammable read-only memory (EPROM), electrically erasable PROM(EEPROM), flash memory, magnetic or optical data storage, registers,etc. Memory is said to be in electronic communication with a processorif the processor can read information from and/or write information tothe memory. Memory that is integral to a processor is in electroniccommunication with the processor.

The terms “instructions” and “code” should be interpreted broadly toinclude any type of computer-readable statement(s). For example, theterms “instructions” and “code” may refer to one or more programs,routines, sub-routines, functions, procedures, etc.

“Instructions” and “code” may comprise a single computer-readablestatement or many computer-readable statements.

The functions described herein may be implemented in software orfirmware being executed by hardware. The functions may be stored as oneor more instructions on a computer-readable medium. The terms“computer-readable medium” or “computer-program product” refers to anytangible storage medium that can be accessed by a computer or aprocessor. By way of example, and not limitation, a computer-readablemedium may comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium that can be used to carry or store desired program code inthe form of instructions or data structures and that can be accessed bya computer. Disk and disc, as used herein, includes compact disc (CD),laser disc, optical disc, digital versatile disc (DVD), floppy disk andBlu-ray® disc where disks usually reproduce data magnetically, whilediscs reproduce data optically with lasers.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isrequired for proper operation of the method that is being described, theorder and/or use of specific steps and/or actions may be modifiedwithout departing from the scope of the claims.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein, suchas those illustrated by FIG. 7, can be downloaded and/or otherwiseobtained by a device. For example, a device may be coupled to a serverto facilitate the transfer of means for performing the methods describedherein. Alternatively, various methods described herein can be providedvia a storage means (e.g., random access memory (RAM), read-only memory(ROM), a physical storage medium such as a compact disc (CD) or floppydisk, etc.), such that a device may obtain the various methods uponcoupling or providing the storage means to the device.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the systems, methods and apparatus described herein withoutdeparting from the scope of the claims.

1. A method for reducing idle mode power consumption, comprising:entering an idle mode; selecting a neighboring base station; if theselected neighboring base station is assigned a high-frequencymonitoring mode: measuring a signal strength of the neighboring basestation; and assigning a low-frequency monitoring mode to the selectedneighboring base station if the signal strength of the selectedneighboring base station has been below a power threshold for longerthan a time threshold.
 2. The method of claim 1, further comprising: ifthe selected neighboring base station is assigned the low-frequencymonitoring mode: measuring the signal strength of the neighboring basestation if it is time to monitor the signal strength; and assigning thehigh-frequency monitoring mode to the selected neighboring base stationif the signal strength of the selected neighboring base station is abovethe power threshold.
 3. The method of claim 2, further comprising:performing a minimum number of power monitors per paging cycle only ifall neighboring base stations are in low-frequency monitoring mode; andperforming more than the minimum number of power monitors per pagingcycle if at least one neighboring base station is assigned thehigh-frequency monitoring mode.
 4. The method of claim 2, furthercomprising maintaining an idle mode timer for each neighboring basestation.
 5. The method of claim 4, wherein the assigning thelow-frequency monitoring mode comprises comparing the idle mode timerfor the selected base station with the time threshold.
 6. The method ofclaim 4, wherein the assigning the high-frequency monitoring modecomprises resetting the idle mode timer for the selected neighboringbase station if the selected neighboring base station is above the powerthreshold.
 7. The method of claim 2, wherein the power threshold andtime threshold are selected to achieve a power reduction in idle modeand maintain performance indicators during operation.
 8. The method ofclaim 2, wherein the method is performed in a Global System for MobileCommunications (GSM) system.
 9. A wireless communication device forreducing idle mode power consumption, comprising: a processor; memory inelectronic communication with the processor; instructions stored in thememory, the instructions being executable by the processor to: enter anidle mode; select a neighboring base station; if the selectedneighboring base station is assigned a high-frequency monitoring mode:measure a signal strength of the neighboring base station; and assign alow-frequency monitoring mode to the selected neighboring base stationif the signal strength of the selected neighboring base station has beenbelow a power threshold for longer than a time threshold.
 10. Thewireless communication device of claim 9, further comprisinginstructions executable to: if the selected neighboring base station isassigned the low-frequency monitoring mode: measure the signal strengthof the neighboring base station if it is time to monitor the signalstrength; and assign the high-frequency monitoring mode to the selectedneighboring base station if the signal strength of the selectedneighboring base station is above the power threshold.
 11. The wirelesscommunication device of claim 10, further comprising instructionsexecutable to: perform a minimum number of power monitors per pagingcycle only if all neighboring base stations are in low-frequencymonitoring mode; and perform more than the minimum number of powermonitors per paging cycle if at least one neighboring base station isassigned the high-frequency monitoring mode.
 12. The wirelesscommunication device of claim 10, further comprising instructionsexecutable to maintain an idle mode timer for each neighboring basestation.
 13. The wireless communication device of claim 12, wherein theinstructions executable to assign the low-frequency monitoring modecomprise instructions executable to compare the idle mode timer for theselected base station with the time threshold.
 14. The wirelesscommunication device of claim 13, wherein the instructions executable toassign the high-frequency monitoring mode comprise instructionsexecutable to reset the idle mode timer for the selected neighboringbase station if the selected neighboring base station is above the powerthreshold.
 15. The wireless communication device of claim 10, whereinthe power threshold and time threshold are selected to achieve a powerreduction in idle mode and maintain performance indicators duringoperation.
 16. The wireless communication device of claim 10, whereinthe wireless communication device operates in a Global System for MobileCommunications (GSM) system.
 17. A wireless communication device forreducing idle mode power consumption, comprising: means for entering anidle mode; means for selecting a neighboring base station; means formeasuring, if the selected neighboring base station is assigned ahigh-frequency monitoring mode, a signal strength of the neighboringbase station; and means for assigning, if the selected neighboring basestation is assigned a high-frequency monitoring mode, a low-frequencymonitoring mode to the selected neighboring base station if the signalstrength of the selected neighboring base station has been below a powerthreshold for longer than a time threshold.
 18. The wirelesscommunication device of claim 17, further comprising: means formeasuring, if the selected neighboring base station is assigned thelow-frequency monitoring mode, the signal strength of the neighboringbase station if it is time to monitor the signal strength; and means forassigning, if the selected neighboring base station is assigned thelow-frequency monitoring mode, the high-frequency monitoring mode to theselected neighboring base station if the signal strength of the selectedneighboring base station is above the power threshold.
 19. The wirelesscommunication device of claim 18, further comprising: means forperforming a minimum number of power monitors per paging cycle only ifall neighboring base stations are in low-frequency monitoring mode; andmeans for performing more than the minimum number of power monitors perpaging cycle if at least one neighboring base station is assigned thehigh-frequency monitoring mode.
 20. The wireless communication device ofclaim 18, further comprising means for maintaining an idle mode timerfor each neighboring base station.
 21. The wireless communication deviceof claim 20, wherein the means for assigning the low-frequencymonitoring mode comprises means for comparing the idle mode timer forthe selected base station with the time threshold.
 22. The wirelesscommunication device of claim 21, wherein the means for assigning thehigh-frequency monitoring mode comprises means for resetting the idlemode timer for the selected neighboring base station if the selectedneighboring base station is above the power threshold.
 23. Acomputer-program product for reducing idle mode power consumption, thecomputer-program product comprising a non-transitory computer-readablemedium having instructions thereon, the instructions comprising: codefor causing a wireless communication device to enter an idle mode; codefor causing the wireless communication device to select a neighboringbase station; code for causing the wireless communication device tomeasure, if the selected neighboring base station is assigned ahigh-frequency monitoring mode, a signal strength of the neighboringbase station; and code for causing the wireless communication device toassign, if the selected neighboring base station is assigned ahigh-frequency monitoring mode, a low-frequency monitoring mode to theselected neighboring base station if the signal strength of the selectedneighboring base station has been below a power threshold for longerthan a time threshold.
 24. The computer-program product of claim 23,further comprising: code for causing the wireless communication deviceto measure, if the selected neighboring base station is assigned thelow-frequency monitoring mode, the signal strength of the neighboringbase station if it is time to monitor the signal strength; and code forcausing the wireless communication device to assign, if the selectedneighboring base station is assigned the low-frequency monitoring mode,the high-frequency monitoring mode to the selected neighboring basestation if the signal strength of the selected neighboring base stationis above the power threshold.
 25. The computer-program product of claim24, further comprising: code for causing the wireless communicationdevice to perform a minimum number of power monitors per paging cycleonly if all neighboring base stations are in low-frequency monitoringmode; and code for causing the wireless communication device to performmore than the minimum number of power monitors per paging cycle if atleast one neighboring base station is assigned the high-frequencymonitoring mode.
 26. The computer-program product of claim 24, furthercomprising code for causing the wireless communication device tomaintain an idle mode timer for each neighboring base station.
 27. Thecomputer-program product of claim 26, wherein the code for causing thewireless communication device to assign the low-frequency monitoringmode comprises code for causing a wireless communication device tocompare the idle mode timer for the selected base station with the timethreshold.
 28. The computer-program product of claim 27, wherein thecode for causing the wireless communication device to assign thehigh-frequency monitoring mode comprises code for causing a wirelesscommunication device to reset the idle mode timer for the selectedneighboring base station if the selected neighboring base station isabove the power threshold.
 29. In a wireless system that comprises aplurality of wireless communication devices configured to communicatewith at least one other wireless communication device, a power savingwireless device configured for reducing idle mode power consumption,said power saving wireless device comprising: a receiver moduleconfigured to receive wireless communication signals from one or more ofa plurality of wireless communication devices; a processor module, inelectronic communication with said receiver module and operating in anidle mode, the processor module configured to determine a signalstrength for each received wireless communication signal, said signalstrength determination being based on comparison with a predeterminedthreshold; the processor module being further configured to assign afrequency state for one or more of the plurality of wirelesscommunication devices based on each determined signal strength thatcorresponds to said one or more of the plurality of wirelesscommunication devices; and the processor module being further configuredto adjust a frequency monitoring mode of said power saving wirelessdevice for each of the plurality of communication devices incommunication with wireless device.
 30. The power saving wireless deviceof claim 29, wherein the processor module is configured to assign atleast one of: (a) a high frequency state to one or more of the pluralityof wireless communication devices when a corresponding signal strengthis above the threshold; and (b) a low frequency state to one or more ofthe plurality of wireless communication devices when a correspondingsignal strength is below the threshold.
 31. The power saving wirelessdevice of claim 29, wherein the processor module is configured tomonitor received signal strengths a minimum number of power monitors perpaging cycle when the frequency state is in a low-frequency monitoringmode.
 32. The power saving wireless device of claim 29, wherein theprocessor module is configured to monitor received signal strengths morethan a minimum number of power monitors per paging cycle when thefrequency state is in a high-frequency monitoring mode.
 33. The powersaving wireless device of claim 29, wherein the processor module isconfigured to maintain an idle mode timer for each of the one or morecommunication devices in communication with the power savings wirelessdevice.
 34. The power savings wireless device of claim 29, wherein thefrequency monitoring mode is at least partially based on the frequencystate.
 35. The power saving wireless device of claim 29, wherein thewireless system is configured as a Global System for MobileCommunications (GSM) system.